There's really nothing more important in your college application than the strength of your academics. Unlike essays and the SATs which can be polished in several weeks, the transcript is a culmination of four years of academic work you did in high school. There's little you can do to change your academic record. That is why admissions officers will always turn to the transcript before anything else. After all, to get an idea of how you will perform next time in college, it's...
There's really nothing more important in your college application than the strength of your academics. Unlike essays and the SATs which can be polished in several weeks, the transcript is a culmination of four years of academic work you did in high school. There's little you can do to change your academic record. That is why admissions officers will always turn to the transcript before anything else. After all, to get an idea of how you will perform next time in college, it's only logical to assess how you've been performing so far.
What courses you take in high school and what grades you get will determine where you end up in September. When colleges look at your folder, the first thing they will see is your transcript. "Has this student challenged herself?" "Are his grades showing an upward trend, declining, or stagnant?" Challenged means taking the toughest courses you can handle.
Please bear in mind that when while you are encouraged to go for the most demanding schedule, you must be able to do well. No point taking the toughest courses if it eats into your social and extra curricular activities. Admissions officers can see that you're trying too hard, and it may instead work against your favor in the college admissions process.
"Is it better to get a B in the Advanced Placement class or an A in the regular class?"
Not surprisingly, this question gets asked a lot of times. Of course, the best thing would be to get an A in the AP class. But seriously, admissions officers would rather you get a B in the AP class. AP classes are much tougher than regular ones, and getting a B - despite the grade itself - shows that you can handle tough workloads.
Just think about it, if A was so important, then every student would try to pad his and her transcript with courses like Getting Slim for the 21st Century just so they could fatten their GPA. That is why grades alone are not enough.
An important thing to note here is that while colleges consider grades, they also consider your performance relative to your classmates. That is where class rank comes in. Class ranks help colleges determine whether the C you got in Calculus is a result of slacking on your part, or a really strict marking system. If your school does not rank, don't despair. Colleges are adept enough at coming up with a ranking for you based on your school profile and academic trend in your school report.
For example, my school does not rank. But my guidance counselor was able to predict my rank as if there was a ranking system, by looking at the performance of my peers in my class that year. So she will write something like "Top 5% of the class this year" for her students. Even if your school policy forbids ranking - as mine do - your transcript can still tell a great deal about what kind of challenges you went through in high school.
Know Your Goals
You academic preparation should also reflect your goals. What kind of school do you want to go to? If you are eyeing for highly selective colleges, then you should take as many AP classes as you can; again, without harming your grades or extra curricular activities.
At the Ivy Leagues and its cousins, you'd probably need all the As you can get from AP classes to have a shot. These academic behemoths are so competitive that a B might (read: I said might because it will still ultimately depend on your overall application strength) not work in your favor.
On the other hand, large state universities use a different rule. These schools attract tens of thousands of applications each year and so they often rely on grades and test scores to make decisions. Here GPA would be more important than the level of courses. In other words, how tough your course selection is isn't necessary, as long as they are college preparatory.
"What if my school does not offer AP courses?"
Don't fret. Designing the curriculum is the responsibility of your school; your job is to take the most challenging ones available. If your school doesn't offer AP English, and every senior takes regular English classes, then yes, that is the most rigorous one. If you come from a really competitive high school, you will be evaluated based on the school's curriculum. Even if you rank near the bottom, there are some schools who will love to take you in since you come from a 'strong' school.
But if your high school isn't so tough, then it may be more important for you to rank near the top.
A really good way to stand out in a selective pool is to go beyond what your school has to offer. This means doing things that are otherwise not offered in your school. If you've studied all the physics courses in school, try taking up advanced courses at a local college. If you love maths and finished calculus in junior year, work with a professor to do research into multivariable equations. These actions show adcoms that you are intellectually curious and always ready to learn new things - a plus point in the admissions process.